1. Field of the Invention
This invention relates to an automated test tube cap removal apparatus for automatically removing caps from test tubes that contain a specimen, such as blood.
2. Description of the Related Art
In a known apparatus for removing caps from test tubes, as described in Jpn. Pat. Appln. KOKAI Publication No. 5-228379, for example, the cap of each test tube is supported by engagement with the distal end portion of a drawing arm in a manner such that the test tubes are held one by one by a test tube retaining member. Then, the drawing arm is raised in a cap drawing direction to automatically draw the cap from the test tube by actuating a lift cylinder with the cap supported by engagement.
The drawing arm has a cap engaging claw at its distal end and is configured to rock the arm-supported cap through a predetermined angular range around its axis in conjunction with a tilt guide as the arm is pulled up by the lift cylinder.
Another example of a known test tube cap removal apparatus is described in Jpn. Pat. Appln. KOKAI Publication No. 2005-271991. In this apparatus, a movable apparatus frame capable of up-and-down motion is disposed above a cap removal portion. A lift mechanism for the movable apparatus frame can lower a descent stop position of a cap engaging chuck from a cap engaging position for large-sized test tubes to a cap engaging position for small-sized test tubes.
The lift mechanism is provided with a vertical ball screw and a drive motor for actuating the screw. As the ball screw is actuated by the drive motor, the movable apparatus frame is moved up and down at strokes corresponding to the test tube size. The test tube is held by a clamping mechanism, and its cap is supported by engagement with a chuck mechanism as it is rotated and raised in a cap disengaging direction, whereby the cap is removed. Even though the test tube size varies or if caps of different types are fitted on the test tubes, therefore, the caps can be removed quickly and accurately from the test tubes.
There are test tubes of various sizes (tube diameters and tube lengths), typically including φ13×75 mm, φ13×100 mm, φ16×75 mm, φ16×100 mm, etc. Further, caps that close the respective openings of the test tubes may be of various types, such as rubber and plastic push-in caps.
However, the test tube cap removal apparatus described above is furnished with the test tube clamping mechanism located in a cap removing position in the middle of a conveying path for conveying each test tube that contains a specimen. When the test tube that is conveyed along the conveying path reaches the cap removing position, it is held by the clamping mechanism. As this is done, the chuck mechanism descends and supports the test tube cap by engagement. The cap is removed by raising the chuck mechanism in rotation in the cap disengaging direction.
Specifically, the test tubes being conveyed along the conveying path are held one by one as they are removed. In uncapping a large number of test tubes that are housed in alignment in, for example, a test tube rack, therefore, the test tubes in the rack must be transferred to the conveying path so that they are carried one after another into the cap removing position as they are uncapped. Thus, the efficiency of cap removal is low.
This invention has been made in consideration of these circumstances, and its object is to provide an automated test tube cap removal apparatus capable of simultaneously uncapping a plurality of aligned test tubes in a test tube rack at a stroke, thereby ensuring high-efficiency test tube cap removal.